Pyvcg

* Add new driver for CVC5 (via SMTLIB files instead of the API).

* Fix python_requires, the expression acidentally excluded Python
3.11. We should now correctly support it.

* Move to CVC 1.0.8. This means we can now support Python 3.11 as
well.

* Pin to CVC5 1.0.5, as 1.0.7 is completely broken

* Fix bug in printing smtlib string literals. They are now correctly
escaped for both quotations and non-printable characters.

* Fix bug when printing smtlib comments with newlines.